The present invention relates to a new and improved switching method for measuring or tracking two neighboring flying targets or objects--hereinafter simply referred to as flying targets--in succession by means of a measuring installation.
The measuring or tracking installation is of the type comprising an electronic observation system having an image sensor and an image device, a regulation system for automatically aligning the image sensor at a flying target to be measured and at least one first image evaluation system. At the image evaluation system there are produced from signals of the observation system a first pair of first deviation signals, respectively constituting a measure of the momentary angular deviation in azimuth and elevation between the direction of a first flying target and the sighting line or line of sight of the image sensor. These signals are delivered to the regulation system in the form of a suitable actual value. There is produced in the observation system an electronic window. At the image device there is framed the trace of the sighting line and there is limited processing of the signals of the observation system in the image evaluation system to such signals which correspond to an image point situated at the image device within the window.
Measuring systems or installations of the aforementioned type are known to the art, for instance, as disclosed in German patent No. 25 02 245. Equally, observation systems of the aforementioned type are also known, for instance, from German patent publication No. 24 41 640. Electronic windows are essentially employed as means for improving the video contrast analysis of the image of a flying target. As for instance has been taught in U.S. Pat. No. 3,736,376, such type installations are designed such that the electronic window and the image of the flying target to be measured are brought approximately to the center of the image at the image device and retained at that location. Equally known are manually actuatable control means. These usually comprise a two-dimensionally movable control knob or stick which, according for instance to the construction disclosed in German patent No. 22 09 073, is capable of placing an electronic window at other image points than at the image center. If the operator sights a flying target to be tracked or measured at the image device, then he or she positions the electronic window with the aid of the control means about the image of the flying target, whereafter there is turned-on an automatic aligning device. Now the image sensor is automatically aligned such that the image of the flying target and the electronic window at the image screen revert towards the image center. The position of the image sensor is continuously measured, as is also the exact position of the image of the flying target at the image device. From such measurements there are derived data concerning the position of the flying target in azimuth and elevation. For military purposes such data is used, for instance, for aiming or aligning anti-aircraft weapons into firing position with respect to the flying target. For civilian purposes there is, for instance, continuously photographed the flying target, and the data concerning the position of the flying target is recorded in a coded form at the film. A typical example of such civilian field of application is the measurement or tracking of rockets, used for instance to launch space capsules and the like. Both, during the design of such rockets and also during starting of such space capsules or the like, it is necessary to be able to exactly determine the position, velocity and acceleration of the flying target. It is exactly in such situation that it is, however, necessary to be able to selectively track, as the point to be measured, the nozzle or the cone of the rocket or to be able to track such according to a random point. Switching of the measuring installation from a mode where there is accomplished measurement of one point into an operational mode where the system measures another point (wherein both points can be, for instance, considered to constitute two neighboring flying objects flying in formation) is associated with alignment errors. These alignment errors are predominantly attributable to time-delays associated with the manipulations carried out by the operator. Even doubling the image evaluation system would not constitute any acceptable solution of the switching problem, because during switching of the regulation system from the one deviation signals to the other deviation signals there are generated build-up or transient phenomena which, in turn, cause measurement errors.